Much the same patterns have held for the developed economies postwar decades. Here, however, one would expect population have a positive impact on economic growth, since growth in the countries increases demand under conditions of high productive ca; To summarize, recent differential rates of change in prod formance have not been obviously related empirically to rates of growth, in either the developed or less developed regions. Moreove rates of output growth have been very similar in both regions over years, the correlation is again essentially zero when the tw< economies are considered in combination. What the data show is that population growth has not beei either to force economic stagnation or to dominate empirical cc However, when the specific causal interrelations involved are view it appears clear that rapid population growth in the less develope has been a decided obstacle rather than an aid to economic grow the more rapid the rise in numbers, the greater the deterrent effect Urbanization. At subnational levels, such as individual urban areas, the cumulative impacts from population change may woi rapidly and have much greater relative importance. However, cle onstration of the welfare and policy implications of subnational movements has been impeded in the past by other kinds of diff well-defined order of social priorities surrounds population sett distribution. The desirability of reduced versus constant fert sharper versus more gradual decline, would hardly seem cause for in the less developed countries. However, the merits of slowe speedier urbanization become murky when their counterpart phi greater as opposed to lesser rural increase are also considered. Exci build-up and agrarian overpopulation tend to be simultaneous ph most less developed countries and no "lesser of two evils" theo developed to compare adequately, much less help choose betweer options they represent. Nor is there a more encompassing met! hand for dealing with entire systems of settlement, in which tov\ and secondary-size cities, in addition to rural areas and primary c be evaluated as alternative residences. Some further considera complex of questions is attempted in other sections of this volume Macro Gains from Lowered Fertility The similar output expansion rates in the developed and les regions since about 1950, coupled with their very different growth rates, have produced a persistently widening gap in theirrds, economic growth in less developed countries has been remarkably rapid, despite record population growth and its anticipated handicaps to development through reduced savings potentials, increased consumption needs, added imports and reduced supplies of foreign exchange, or lagging investment per unit of labor.